When people join their voices in song, their hearts come along for the group ride, speeding up, slowing down and (figuratively) swelling in unison while much of the chorale's muscular movement and brain activity synchronizes as well.

Now Swedish researchers are examining whether it might be harnessed for strengthening working relationships in teams and at schools.

The research, released in the open-access journal Frontiers in Neuroscience, is the latest to explore the health benefits of making music. It's already been found that learning to play a musical instrument can have long-term cognitive benefits, and that listening to music can lower blood pressure, ease pain and provide connections to happier, healthier times and memories.

That it can synchronize the heartbeats of choral singers very quickly offers a health benefit that's harder to characterize. In individuals, the Swedish researchers found, singing of several different kinds imposes a calm breathing pattern, and increases heart rate variability, the routine changes in heart rate that are considered a measure of "good autonomic tone." The long exhalations that singers use to sing long phrases appears to stimulate the vagus nerve, slowing the heart and achieving the kind of relaxation seen in practitioners of yoga.

But when a whole group experiences these benefits, the effect may be multiplicative. Synchrony, and the rituals that instill it, provides a sense of social belonging, which can ward off loneliness and the substantial health risks that attend it. And if a greater sense of cooperation ensues, groups relying on teamwork might work more productively. Overeating cycles: Digging into a breakfast of buttermilk pancakes and maple syrup, or a great bowl of white pasta for lunch, sends your blood sugar soaring and then, suddenly, plummeting. But four hours after you've put down your fork, such a meal makes you hungrier than if you'd eaten one with more protein and fiber and fewer carbohydrates, a new study finds.

The study also demonstrates that four hours later, the echo of that meal activates regions of the brain associated with craving and reward-seeking more powerfully than does a meal with a lower "glycemic load."

The result:At your next opportunity to eat, you'll not only be hungrier, you'll be looking for more of the same.

The study, conducted by researchers from Harvard Medical School and Boston Children's Hospital, was published in the American Journal of Clinical Nutrition. The team was led by Dr. David S. Ludwig, director of Boston Children's Hospital Obesity Prevention Center and author of "Ending the Food Fight: Guide Your Child to a Healthy Weight in a Fast Food/Fake Food World."

And what's the result of repeating this cycle meal after meal? The Harvard researchers surmise that the striatum, a key node in the brain's reward circuitry, may lose its sensitivity to the neurotransmitter dopamine, increasing a person's drive to eat high-carb foods and disrupting his or her ability to control that impulse.

The combination of plummeting blood sugar levels, a greater sensation of hunger, and a memory of a meal high on the glycemic index led to the researchers' conclusion: "This combination of physiological events may foster food cravings with a special preference for high (glycemic load) carbohydrates, thereby propagating cycles of overeating."